13 April 1968
On 30 May 1967, Biafra declared itself independent from Nigeria. This region comprised roughly the south-eastern provinces of Nigeria. This declaration came after two military coups and two major pogroms against the Igbo (Ibo) people in Nigeria. The Igbo people constituted the majority of the population in the seceded territory. Among the reasons for the succession was that the more populous northern provinces of Nigeria were dominating the southern provinces. There was also an ethnic and religious dimension to the split.  The Southern states were made up of  ethnic Igbo, who were Christians, while the North comprised mostly Yoruba and Hausa-Fulani who belonged to the Muslim faith. Nyerere, then President of Tanzania, supported this move by the Biafrans on the basis of ongoing instability due to domination by Northern Nigeria, the numerous pogroms endured by the Igbo people, the fact that post- independence Nigeria's borders were based on the expansion of colonialism, in particular British imperialism, that Nigeria had reneged on a system of government it had agreed upon during its negotiations toward independence,  that Biafra was formed due to the severe persecution suffered by the Igbo people, and that rejoining Nigeria, would mean certain death. On 13 of April 1968, Tanzania became the first country to recognise the independence of Biafra.
References

Statement by the Minister of State (Foreign Affairs) Mr. C. Y. Mgonja at State House on Tanzania's recognition of Biafra,[online], Available at:  biafraland.com [Accessed: 11 April 2014]| Nyerere.J, Biafra, Human Rights and Self-Determination in Africa [online], Available at: usafricaonline.com  [Accessed: 11 April 2014]| Biafra/Nigeria [online], Available at: enotes.com [Accessed: 11 April 2014]